/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package wx.xml.xalan.xml.utils;

/**
 * This class pools string buffers, since they are reused so often.
 * String buffers are good candidates for pooling, because of
 * their supporting character arrays.
 *
 * @xsl.usage internal
 */
public class StringBufferPool {
    /**
     * The global pool of string buffers.
     */
    private static ObjectPool m_stringBufPool =
        new ObjectPool(wx.xml.xalan.xml.utils.FastStringBuffer.class);

    /**
     * Get the first free instance of a string buffer, or create one
     * if there are no free instances.
     *
     * @return A string buffer ready for use.
     */
    public synchronized static FastStringBuffer get() {
        return (FastStringBuffer) m_stringBufPool.getInstance();
    }

    /**
     * Return a string buffer back to the pool.
     *
     * @param sb Must be a non-null reference to a string buffer.
     */
    public synchronized static void free(FastStringBuffer sb) {
        // Since this isn't synchronized, setLength must be
        // done before the instance is freed.
        // Fix attributed to Peter Speck <speck@ruc.dk>.
        sb.setLength(0);
        m_stringBufPool.freeInstance(sb);
    }
}
